Solar Energy Collection Panel Cleaning System

ABSTRACT

An apparatus, method and system for cleaning a solar panel includes a solar panel, one or more fluid reservoirs, a fluid dispenser at a first side of a solar panel, a mechanism for providing pressurized fluid to the fluid dispenser from the fluid reservoir(s), and a mechanism for dispensing the fluid from the dispenser. The solar panel is periodically cleaned and the motivation for cleaning may be a detected output condition of the panel, a detected weather condition, an expired time condition, detected precipitant accumulation, a manual command, or the like. The fluid(s) may include a gas and/or one or more liquids. A heater may be provided to heat the fluid(s).

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a United States National Stage Applicationfiled under 35 U.S.C. § 371 of International Application No.PCT/US2016/035852, entitled “Solar Energy Collection Panel CleaningSystem,” which was filed on Jun. 3, 2016 which claims the benefit of,and priority to, U.S. Provisional Patent Application Ser. No. 62/171,817filed on Jun. 5, 2015, the disclosure of which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to a system, apparatus andmethod for cleaning solar energy collection panels such as reflectivesolar concentrator panels and photovoltaic panels.

BACKGROUND

The term “solar energy collection panel” (or “panel”) as used herein isintended to include reflector-type panels (e.g., mirrors) used inheliostats as well as photovoltaic (“PV”) panels which directly convertsolar energy to electrical energy. Solar energy collection panels, or“solar panels”, are generally deployed outdoors and are exposed to dirt,dust, sand, precipitation, and the like which tend, over time, tointerfere with the transmission of solar energy to the panel and toreduce the efficiency of such panels. What is desired is a system andmethod for efficiently and inexpensively cleaning solar panelsperiodically to maintain their output.

OVERVIEW

An apparatus, method and system for cleaning a solar panel includes asolar panel, one or more fluid reservoirs, a fluid dispenser at a firstside of a solar panel, a mechanism for providing pressurized fluid tothe fluid dispenser from the fluid reservoir(s), and a mechanism fordispensing the fluid from the dispenser. The solar panel is periodicallycleaned and the motivation for cleaning may be a detected outputcondition of the panel, a detected weather condition, an expired timecondition, detected precipitant accumulation, a manual command, or thelike. The fluid(s) may include a gas and/or one or more liquids, and inthe case of liquid(s) a fluid collector may be provided at a second sideof a solar panel and utilized to collect at least some of the fluidwhich may then be directed optionally to a filter and then optionally toan appropriate reservoir for reuse or disposal.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more exemplary embodimentsand, together with the description of the exemplary embodiments, serveto explain the principles and implementations of the invention.

In the drawings:

FIG. 1 is a schematic diagram of a solar panel in accordance with anaspect of the invention.

FIG. 2 is a process flow diagram for cleaning a solar panel inaccordance with an aspect of the invention.

FIG. 3 is a system block diagram illustrating the control system andsensors used in accordance with an aspect of the present invention.

FIG. 4 is a top plan view of a fluid manifold assembly in accordancewith an aspect of the present invention.

FIG. 4A is a cross-section taken along lines 4A-4A of FIG. 4illustrating in detail an aspect of the present invention.

FIG. 5 is a top plan view of a fluid manifold assembly in accordancewith an aspect of the present invention.

FIG. 5A is a cross-section taken along lines 5A-5A of FIG. 5illustrating in detail an aspect of the present invention.

FIG. 6A is a cross-sectional diagram illustrating an extendable fluiddispenser in a retracted state in accordance with various embodiments.

FIG. 6B is a cross-sectional diagram illustrating an extendable fluiddispenser in an extended state in accordance with various embodiments.

FIG. 6C is a detailed schematic diagram illustrating a coil-typeelectrical water heater disposed at the nozzle of a fluid dispenser inaccordance with various embodiments.

FIG. 7 is a schematic diagram of a solar panel in accordance with anaspect of the invention illustrating various embodiments incorporatingextendable fluid dispensers and transducers.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Exemplary embodiments are described herein in the context of a solarenergy collection panel cleaning system. Those of ordinary skill in theart will realize that the following description is illustrative only andis not intended to be in any way limiting. Other embodiments willreadily suggest themselves to such skilled persons having the benefit ofthis disclosure. Reference will now be made in detail to implementationsof the exemplary embodiments as illustrated in the accompanyingdrawings. The same reference indicators will be used to the extentpossible throughout the drawings and the following description to referto the same or like items.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions must be madein order to achieve the developer's specific goals, such as compliancewith application- and business-related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

References herein to “one embodiment” or “an embodiment” or “oneimplementation” or “an implementation” means that a particular feature,structure, part, function or characteristic described in connection withan exemplary embodiment can be included in at least one exemplaryembodiment. The appearances of phrases such as “in one embodiment” or“in one implementation” in different places within this specificationare not necessarily all referring to the same embodiment orimplementation, nor are separate and alternative embodiments necessarilymutually exclusive of other embodiments.

In accordance with this disclosure, the components, process steps,and/or data structures described herein may be implemented using varioustypes of operating systems, computing platforms, computer programs,and/or general purpose machines. In addition, those of ordinary skill inthe art will recognize that devices of a less general purpose nature,such as hardwired devices, field programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), or the like, may alsobe used without departing from the scope and spirit of the inventiveconcepts disclosed herein. Where a method comprising a series of processsteps is implemented by a computer or a machine and those process stepscan be stored as a series of instructions readable by the machine, theymay be stored on a tangible medium such as a computer memory device(e.g., ROM (Read Only Memory), PROM (Programmable Read Only Memory),EEPROM (Electrically Eraseable Programmable Read Only Memory), FLASHMemory, Jump Drive, and the like), magnetic storage medium (e.g., tape,magnetic disk drive, and the like), optical storage medium (e.g.,CD-ROM, DVD-ROM, paper card, paper tape and the like) and other types ofprogram memory.

In accordance herewith a solar energy collection panel cleaning systemcomprises a combination of an apparatus, software controlling automatedaspects of the apparatus and a method for cleaning fully assembled andinstalled solar energy collection panels (concentrator panels, reflectorpanels and photovoltaic panels) periodically or an adhoc basis whetherdeployed on a commercial rooftop, residential rooftop, or in aground-mounted solar farm configuration to clean the panel surfacethereby reducing loss caused by atmospherically deposited material suchas dirt, dust, sand, precipitation and the like. The cleaning may beinitiated in response to a detected output condition of the panel, adetected or expected future weather condition, an expired timecondition, detected precipitant accumulation, a manual command, or thelike.

A purpose of the invention is to restore surface integrity of the panelso that it can capture (or reflect) as much light as possible given thatobstructions on the panel surface impact output and hence the economicsof the energy being produced. The cleaning approaches described hereinare applicable to all types of solar panels, e.g., crystallinesemiconductor, thin film based (cadmium telluride, amorphous silicon,copper indium gallium diselenide or any other type), polycrystallinesemiconductor, mirror, concentrator-type, fixed or tracked that is beingdeployed and can be customized according to the dimensions of the paneland its orientation (fixed or rotating by means of a solar trackersystem).

While commercially available PV solar panels are commonly warranted for20 or more years, the real challenge in terms of sustained output forusers comes from a host of external factors, particularly the weather.Snow, ice, sleet, sand or dust particles present on the surface of thepanel can adversely affect the net efficiency of the panel by obscuring,attenuating or deflecting sunlight to be captured/reflected. Since suchobscuring, attenuating or deflecting adversely affects the economics ofthe panel, a practical approach to restoring the panel to its initialclean state is to use an automated system to monitor and clean the panelin an appropriate manner at an appropriate time. Since adjacent panelsmay have different contamination levels, in accordance with an aspect ofthe invention each panel or group of panels in an array may be providedwith its own system for determining when to clean the panel or group ofpanels in the array.

The apparatus, systems and methods detailed herein are directed tocleaning solar panels manually or automatically so that more useableenergy can be collected over time.

The disclosure describes (a) hardware which may be associated with thepanel and may be customized for a particular installation in order tocarry out the cleaning process; (b) various cleaning processes which maybe implemented with the hardware; (c) sensor (and other) systems whichmay be utilized to make the decision to start the cleaning process; and(d) control systems for utilizing the sensor data to make the startdecision and carry out the cleaning process. Optionally feedback systems(such as sensors or video) may be incorporated to determine when thecleaning process has completed its task or run into an impasse so as tomake the cleaning process more efficient and alert a human (or robotic)operator to a problem which requires attention.

The hardware that adapts a solar panel for cleaning in accordance withan aspect of the present invention includes a weatherproof fixturedeployed along at least a first edge (generally the upper-most edge) ofa panel. The fixture comprises at least one manifold or a plurality ofconduits such as pipes for carrying the cleaning fluid (liquid or gas)to the fixture. A plurality of nozzles or diffusers (collectivelyreferred to as “nozzles”) on the fixture, which may be placed at evenspacings if desired, direct the fluid into contact with the uppersurface of the panel for cleaning purposes.

In accordance with one aspect of the invention, a plurality of differentfluids may be made available to the fixture using partially common orentirely separate conduits from separate fluid reservoirs in order toprovide more than one cleaning mode for the panels. Separate nozzles maybe employed for the different fluids if desired. For example, inaccordance with an aspect of the invention, compressed air (gas), water,and ethylene glycol may be separately provided to clean the panel inresponse to a variety of conditions.

FIG. 1 is a schematic diagram of a solar panel 10 in accordance with anaspect of the invention. A solar panel 10 as shown in FIG. 1 is mountedto a platform comprising supports 12 a, 12 b. A fluid reservoir 14 maystore a pressurized fluid such as a liquid or a gas for deployment viapath 16 (which may be, for example, a pipe) to a dispenser 18 which maybe a manifold or similar device with one or more nozzles 20 throughwhich the fluid is emitted and directed against the upper surface 22 ofpanel 10. In one embodiment the fluid, if a liquid, may be collected bycollector 24 which may be a trap, trough or similar device and which maybe assisted by a vacuum device, or not, depending upon the application.Fluid collected by the collector is directed via path 26 (which may be,for example, a pipe) to filter 28 where dirt and other impurities areremoved before the fluid is recycled back into reservoir 14.

The fluid may be a pressurized gas such as pressurized air or nitrogenor the like used to blow dirt from the upper surface 22 of panel 10.Similarly, it may be a liquid such as water, alcohol, ethylene glycol(EG), some combination thereof and/or a selectable choice of one or moreof the above, or the like. Water may be used for a simple regularcleaning. EG may be used if accumulated snow or ice is expected ordetected (using, for example, visual detectors, weather information(commonly available from a number of sources in electronic format),temperature sensors, other sensors or manual sensing). Where desirablethe liquid may be recycled rather than deployed into the environment.Additionally, a heater 30 may be provided to warm the fluid prior todeployment to increase its cleaning efficiency where desired.Anti-siphon valves may be used to prevent backflow if required.

FIG. 2 is a process flow diagram illustrating an aspect of theinvention. A conventional control system may implement the process 40 ofFIG. 2. One or more reservoirs 14 containing a cleaning fluid (gas orliquid) are pressurized at step 42. When pressurized (as detected, forexample, by a pressure sensor), valves deployed between the reservoirsand the dispenser 18 are opened 44 to allow the fluid to flow to thepanel surface 46. Once the period for cleaning is over they are closedagain. The period for cleaning may be a fixed period or based upon acalculation by the control system, or based upon feedback provided byone or more sensors deployed to monitor the solar panels. For example,where snow and ice is a concern a low-power laser could be targeted atan oblique angle to the surface of the panel and its reflectionmonitored. Only where there was a buildup of ice/snow would thereflection be detected above a certain threshold and this sensor couldbe used to detect snow/ice accumulation and could be used to operate thecleaning cycle until the snow/ice accumulation was dissipated.Optionally liquid fluid may be collected 48 at collectors 24, optionallyfiltered or otherwise cleaned 50 and optionally recycled for reuse tothe respective reservoir 52.

FIG. 3 is a system block diagram illustrating the control system andsensors used in accordance with an aspect of the present invention. Aconventional computer-based control system 60 may have inputs asfollows: Timer/clock 62, temperature sensor 64, snow/ice accumulationdetector 66, solar energy output sensor 68 (which may be provided byanother system monitoring the output of the solar panels), and manualinput 70 (provided to allow an operator to command a cleaning cyclemanually regardless of sensor state). In this version three separatepressurizable reservoirs 72, 74 and 76, corresponding valves 78, 80 and82, and corresponding fluid heaters 84, 86 and 88 are provided andcontrolled by control system 60. Control system 60 monitors the sensorsin addition to optional weather data provided electronically andoperates the cleaning system accordingly. For example, prior to an icestorm it could be programmed to deploy EG to reduce the accumulation ofice on the panels and make a subsequent cleaning cycle easier. Where theweather conditions are dry but a drop in output is detected it could beprogrammed to deploy high pressure gas to blow dust from the panelsurface, and the like.

Turning now to FIGS. 4 and 5, FIGS. 4 and 5 illustrate a top plan viewof versions of a fluid manifold assembly 18 in accordance with variousaspects of the present invention. FIGS. 4A and 5A respectivelyillustrate cross-sections taken along lines 4A-4A of FIGS. 4 and 5A-5Aof FIG. 5 illustrating in detail further aspects of the presentinvention.

In accordance with one example embodiment the hardware component mayinclude a manifold plate or a plurality of tubes or conduits (typically2-6) encased in a weatherproof case (collectively referenced by ‘18’)running along an edge of the solar panel. These tubes will have openingsfor nozzles (18-1), which are placed, at periodic distances across theedge of the panel. The manifold plate may include tubes or conduits forair and liquid delivery, nozzles for delivering pressurized gas to thepanel, porous plates (18-2) for gas delivery and may include one or moresensors for detecting debris or snow levels. Such sensors, if desired,may alternatively be deployed in other locations. The manifold, tubes,porous plates and nozzles are used to dispense fluid via one or morechannels or paths. Fluids may comprise compressed gas (e.g., compressedair, compressed Nitrogen) with an option for heating, chemicals or watermixed with a chemical such as EG or another alcohol used to cleandebris/precipitation from the panel, water used for general purposeperiodic cleaning. The heaters may be incorporated into the respectivereservoirs or separate, as desired.

A diffuser plate 18-2 having a matrix of pores (which may be of similarsize or different sized) may be used to create a flow of pressurized gasover the surface of the panel. It may be fabricated with a metal,composite, ceramic-composite or other appropriate material. Pressurizedair from the diffuser may be formed into a “curtain” of gas whichassists in removing debris from the panel. It may be used in conjunctionwith nozzles 18-1 for deploying liquid, or instead of nozzles.

Optionally spent liquid fluid may be collected for disposal orrecycling. A collector such as a trough or gutter may be deployed at thelower end of the panel to collect spent liquid. The liquid may then bedirected toward a disposal system or toward filtration and recyclingequipment to clean the fluid and return it to the appropriate reservoir.The process may also be controlled by control system 60.

Finally, in terms of determining the efficacy of the cleaning process,diagnostic hardware which includes LED sources and LED detectionphotodetectors to determine if the panel surfaces are clear or not mayalso be deployed under control of the control system 60. This may beaccomplished by measuring the magnitude of the signal from LED sourcesthat would arrive unattenuated if there was no debris on the surface ofthe panel. By placing multiple LEDs and sensors (these can be arrangedvertically if need be), it would be possible for example to know howmuch snow was present and how much is still remaining after cleaning. Anonboard camera anchored to the hardware could also be positioned at keylocations to qualitatively survey the extent of the clean. The lasersystem described above might also be used.

Where heavy snow/ice accumulation is an issue a load cell or similardevice could be used to detect snow/ice accumulation and determine whenit had been abated by the cleaning process.

In accordance with another embodiment, for areas where the predominantconcern is snow and/or ice buildup, a fluid dispenser may be implementedas follows. One or more extended or extendable fluid dispensers may bemounted to the solar panel. An extended dispenser would simply extendabove the plane of the panel in a fixed manner. An extendable dispenserwould operate under electronic, mechanical or hydraulic control toextend upon demand above the plane of the panel (for example, forcingpressurized water through it could cause it to extend if the nozzle werelimited in size—much like a pop-up garden sprinkler). From the extendedposition the dispenser would release optionally heated fluid forcleaning the panel and the nozzle would not remain imbedded in theaccumulated snow or ice facilitating snow/ice removal. A pop-up typedispenser would be configured to retract when not needed. Additionally atransducer may be attached to the panel to help shake snow/ice from thepanel in conjunction with the application of fluid.

Turning in more detail to FIGS. 6A, 6B and 7, FIG. 6A illustrates anextendable (pop-up) type of fluid dispenser 90 in a retracted state.Pressurized and optionally heated fluid such as water enters dispenser90 at input 92 and exits at nozzle 94 from which it is dispensed towardthe surface of the panel (10 in FIG. 7). By limiting the size of nozzle94 and applying adequate pressure to the fluid at input 92 dispenser 90may be forced to expand so that nozzle 94 moves upward relative to theplane of the panel (as shown in FIG. 6B) penetrating any accumulatedsnow/ice so that fluid exiting nozzle 94 may descend to help remove theaccumulated snow/ice on the panel.

In one embodiment the fluid may substantially comprise water heated to atemperature in excess of 80 degrees centigrade. In another embodimentthe fluid may substantially comprise water heated within a range of80-99 degrees centigrade. In another embodiment the water may beelectrically heated at the nozzle outlet as shown in FIG. 6C by acoil-type electrical water heater 95 to a temperature in excess of 80degrees centigrade without concern for reaching a boiling point withinthe system itself.

In one embodiment various forms of transducers may be added andmechanically coupled to the panel in various ways to induce shaking ofthe panel which, in conjunction with the application of fluid willenhance and speed up the snow/ice removal process. For example atransducer 96 may be applied to the back of the panel, a transducer maybe applied to the side of the panel, a transducer, such as apiezoelectric transducer, may be imbedded within or to the glass uppersurface of the panel. In each case the transducer would be controlled bythe controller 60 or a similar device working in conjunction therewith.A simple mechanical transducer may be formed of an eccentric weight spunby an electrical motor or the like and similarly controlled bycontroller 60 or a similar device working in conjunction therewith.

While exemplary embodiments and applications have been shown anddescribed, it would be apparent to those skilled in the art having thebenefit of this disclosure that numerous modifications, variations andadaptations not specifically mentioned above may be made to the variousexemplary embodiments described herein without departing from the scopeof the invention which is defined by the appended claims.

What is claimed is:
 1. A solar panel, comprising: a solar energycollection surface and a cleaning system comprising, (a) a controlsystem; (b) a fluid reservoir; (c) a fluid dispenser disposed at aperimeter of the panel and including a nozzle for emitting a fluid, thenozzle configured to dispense the fluid over the solar energy collectionsurface; (d) a valve connected to the fluid reservoir and the controlsystem, and configured to release the fluid to the dispenser uponcommand from the control system; and (e) a heater connected to thecontrol system; wherein the nozzle is an electrically heated nozzlecomprising the heater; wherein the control system controls a cleaningcycle by selective release of fluid at a controlled temperature bycommand to the valve and the heater.
 2. The solar panel of claim 1,further comprising: a mechanism configured to extend the nozzle of thefluid dispenser above a plane defined by the panel while dispensing thefluid from the dispenser.
 3. The solar panel of claim 1, furthercomprising: a transducer connected to the control system and configuredto shake or vibrate the panel upon command from the control system. 4.The solar panel of claim 1, further comprising: a fluid collectordisposed at a second side of the panel-opposite a first side andconfigured to collect at least a portion of the fluid dispensed by thedispenser; a filter configured to filter fluid collected at the fluidcollector; and a path to convey fluid from the filter to the fluidreservoir.
 5. The solar panel of claim 1, wherein the fluid reservoircomprises a plurality of fluid reservoirs each connected to anassociated valve, and each associated valve is connected to the controlsystem.
 6. The solar panel of claim 1, wherein the fluid compriseswater.
 7. The control system of claim 1, wherein the fluid comprises analcohol.
 8. The solar panel of claim 1, wherein the electrically heatednozzle is a coil-type heater.
 9. The solar panel of claim 1, wherein thefluid is a gas.
 10. The solar panel of claim 1, wherein the heater isconfigured to heat the fluid to a temperature exceeding 80 degreescentigrade.
 11. The solar panel of claim 1, further comprising a sensorfor detecting weather conditions, the sensor providing sensor data tothe control system.
 12. The solar panel of claim 11, wherein the sensorfor detecting weather conditions comprises one or more of a temperaturesensor, a visual detector, a camera, a solar energy output sensor, aload cell, a laser, and a light emitting diode.
 13. The solar panel ofclaim 11, wherein the control system is configured to carry out thecleaning cycle based on the sensor data.
 14. The solar panel of claim 1,wherein the control system is configured to carry out the cleaning cyclebased on weather conditions provided as data to the control system. 15.The solar panel of claim 1, wherein the control system comprises a timerand the control system is configured to carry out the cleaning cyclebased on a time condition provided by the timer.
 16. The solar panel ofclaim 1, wherein the control system comprises a manual input and thecontrol system is configured to carry out the cleaning cycle based onthe manual input.
 17. The solar panel of claim 1, wherein the fluidreservoir is configured to store a pressurized fluid.
 18. The solarpanel of claim 17, wherein the fluid is a gas.
 19. The solar panel ofclaim 17, wherein the fluid is a liquid.
 20. An array of solar panelscomprising two or more solar panels according to claim 1.